1. Field of the Invention
The invention relates to a cutting method of flat wire, and a cutting tool.
2. Description of Related Art
Japanese Patent Application Publication No. 2014-060860 (JP 2014-060860 A) describes film stripping device that strips a film from film-covered flat wire. The film stripping device described in JP 2014-060860 A has a rotating shaft that is parallel to a length direction of the flat wire, and transports the flat wire in a direction orthogonal to the rotating shaft. Then, with the flat wire positioned in the length direction, a plurality of processing means for carrying out processing in the same direction processes an end portion of the flat wire.
In this way, with the technology described in JP 2014-060860 A, a plurality of processing means processes the end portion of the flat wire. More specifically, the plurality of processing means involves chamfering a conductor of the flat wire, and stripping the film off of each side surface of the flat wire. Therefore, the number of processes is large, so the entire process is complicated. Furthermore, when chamfering the conducting wire and stripping off the film, processing must be done with a different cutting tool at different stations. That is, a station is required for each processing process, so a large number of stations are required.
One example of a related cutting method will be described with reference to FIGS. 12 and 13. FIG. 12 is a flowchart illustrating a related cutting method. FIG. 13 is a perspective view of the structure of a flat wire 20 in the processing processes. The flat wire 20 is a film-covered flat wire in which a film 22 is provided on an outer periphery of a conductor portion 21. Also, in FIG. 13, the Y direction is the length direction of the flat wire 20, the X direction is the width direction, and the Z direction is the thickness direction.
First, in order to mark a cutting location, the film 22 is stripped at a portion of the cutting location (S101). As a result, a portion of the conductor portion 21 is exposed such that the structure shown in A of FIG. 13 is obtained. Then the film 22 is vertically precut (S102). The film 22 on two opposing side surfaces of the flat wire 20 is precut, such that the structure shown in B of FIG. 13 is obtained. Here, the film 22 is precut along two precut lines P1 that are parallel to the X direction.
Next, the film 22 is laterally precut (S103). As a result, the film 22 on the two remaining surfaces of the flat wire 20 is precut such that the structure shown in C of FIG. 13 is obtained. Here, the film 22 is precut at precut lines P2 that are parallel to the Z direction. In the Y direction, the precut lines P2 are in the same positions as the precut lines P1. Next, when the precut film 22 is laterally stripped (S104), the structure shown in D of FIG. 13 is obtained. Here, the film 22 is stripped between the two precut lines P1, on two opposing side surfaces of the flat wire 20. As a result, the conductor portion 21 is exposed. Then, when the flat wire 20 is cut (S105), the structure shown in E of FIG. 13 is obtained.
Next, chamfering is performed on the cut portion of the flat wire 20. Therefore, a tip end portion of the cut portion of the flat wire 20 is vertically chamfered (S106). Here, chamfering is performed on one end of the cut surface. As a result, the structure shown in F of FIG. 13 is obtained. In F of FIG. 13, the shaded area is chamfered. Next, a tip end portion of the cut portion of the flat wire 20 is laterally chamfered (S107). Here, chamfering is performed on both ends of the cut surface. As a result, the structure shown in G of FIG. 13 is obtained. In G of FIG. 13, the shaded areas are chamfered.
Next, the film 22 is stripped from corner portions of the chamfered tapered surface (S108). Here, the film 22 at the location indicated by the arrow in H of FIG. 13 is stripped off. Similarly, the film 22 is stripped from a corner portion of the chamfered tapered surface (S109). Here, the film 22 at the location indicated by the arrow in I of FIG. 13 is stripped off. Then, the film 22 of the two opposing side surfaces of the flat wire 20 is vertically stripped (S110). As a result, the film 22 of the entire cut portion of the flat wire 20 is stripped, such that the conductor portion 21 is exposed, as shown in J of FIG. 13.
In this way, the flat wire 20 is cut via 10 processing processes. Therefore, 10 different stations are required. A reduction in the number of processing processes is desired to reduce the number of stations.
Moreover, when the conductor portion 21 is formed from a conducting wire assembly, each twisted wire is independent. Therefore, when the flat wire 20 without the film is cut by a cutting tool 51, as shown in FIG. 14A, the twisted wires of the conducting wire assembly may separate, as shown in FIG. 14B, from the cutting force of the cutting tool 51, or the end portion of the cut location may deform, as shown in FIG. 14C, from the cutting force of the cutting tool 51.